The human spine is formed from twenty-six consecutive vertebrae. Each of these vertebrae is separated from any adjacent vertebra by an intervertebral disc that functions to absorb shock and prevent each vertebra from directly impacting upon another vertebra. At the center of each disc is a nucleus pulposus that contains proteoglycan. Around the nucleus pulposus is an outer ring called the annulus fibrosus. Degenerative disc disease refers to any of the common degenerative conditions of the spine involving degeneration of the disc. Disc degeneration is often associated with the symptom of pain and may lead to inflammation and neuropathic pain, for example, spinal stenosis, spondylolisthesis, and retrolisthesis.
Disc degeneration associated with the aging process is generally associated with the loss of proteoglycan from the nucleus pulposus of the spinal discs and a reduction of the disc's ability to absorb shock between vertebrae. Although some affected patients may not exhibit symptoms, many affected patients suffer from chronic back or neck pain in addition to arm and/or leg pain. Pain associated with disc degeneration may become debilitating and may greatly reduce a patient's quality of life.
Treatments for intervertebral disc herniations include open or mini-open surgery, using very small opening incisions or percutaneously, utilizing specially designed instruments and radiographic techniques to target the pain generator or area that is involved in the painful condition.
Unfortunately, particularly with pain generators in the spine, the cause for the back or neck pain may be difficult to diagnose, as there are numerous structures containing nociceptors and often the pain radiates throughout the back or neck region. To complicate matters for the practitioner, the vertebrae of the spine look very similar and are often no more than an inch tall with only a small separation between their bony structures. Sometimes, particularly when the spine is injured or abnormal, it may be difficult to locate the injured or abnormal vertebrae involved in causing the pain. Often times the practitioner will take additional steps such as taking several X-rays, MRIs, CAT scans, and counting the number of vertebrae to ensure the right vertebra is being treated. MRI and CT myelograms can detect anatomical changes associated with degeneration of the disc but they have no predictive value since it is well known that a really abnormal looking disc may not be painful and a minimally disrupted disc may be associated with severe pain. Alternative tests are based on injection of pain-provocating or local anesthetic fluid into the disc (i.e. discography) while the patient is asked if the procedure “reproduces exactly” or “annihilates completely” his/her original pain symptoms. These tests are of a very invasive and subjective nature and their predictive value remains controversial. In addition, the discography procedure can actually trigger disc herniation at the site of injection.
The practitioner, sometimes, will let the disease degeneration and pain progress to a later stage to get a better understanding of the pain generator before starting treatment. Over time, the pain often radiates outside the back or neck region, for example into the arm or leg which is often caused by severe bulging of the disc that causes a pressure on the adjacent nerve root. The path of the radiating pain symptoms gives a better indication of which nerve root and spinal level is affected. Unfortunately, at this advanced stage of degeneration, the non-surgical treatment options are limited.
In spite of these additional steps, sometimes the wrong vertebra is indeed treated, which subjects the patient to additional surgeries. The patient will often feel afraid or depressed and this may prevent full participation in general rehabilitation programs and may even slow recovery. Thus, there is a need to improve the diagnosis of degenerative disc disease to increase the success rate of the currently available treatments and allow for the development of early and less invasive interventions. There is also a need to reduce surgical errors from practitioners operating on the wrong intervertebral disc.